Hello, I want to buy a USB 2.0 HUB for my MacBook. I plan to plug an external hard drive into it, a mouse and a printer (maybe an ipod to charge too). Does it need a hub with power supply? All the devices will rarely be going simultaneously. It would be the mouse and hard drive most of the time. But I'd be editing video on the hard drive or Time Machine would be backing up data on it. Thanks, just a little confused with the power or no power aspect.